Extension cord



`Mami: 25 1924.

L. A. GRIFFIN EXTENSION CORD Filed nec. 1o 1921 2 sheds-sheet 1 BASZQB? March 25 1924.

L. A. GRIFFIN EXTENSION CORD Filed Dec. 1o. 1921 2 Shees-Sheet 2 Wu u, mkv Sw@ 1 mh m| ,mm wm M Mw @NNN mi Patented Mar. 25, 1924.

I-ORNE A. GRIFFIN, OF EVANSTON, ILLINOIS.

EXTENSION CORD.

To all whom t may cof/wem:

Be it known that I, LonNr. A. GRIFFIN, a citizen of the United States, and resident of Evanston, in the county of Cook and State of Illinois, have invented a. certain new and useful Improvement in Extension Cords, of which the following is a full, clear, concise, and exact description, reference being made to the accompanying drawing, forming a part of this specification.

This invention relates to extension cords for electric circuits. The object of the invention is the provision of an extension cord which shall be capable of standing severe or long continued usage, and one which is adapted to be used in damp or wet places.

One of the features of the present invention is the provision of a waterproof coveringI about the conductors of the cord which also extends about the terminal contact block, so as to provide a water tight joint at the point where the conductors enter the terminal block.

Another feature of the invention is the provision of a rim extending from the edge of the waterproof covering beyond the terminal block which may be employed to provide a Water tight connection between the terminal block and some article associated therewith, as, an electric light bulb.

Another feature of the invention is the provision of anchor wires or cords, each of which has one end joined to the terminal block, the remaining portion of the anchor strip being imbedded in the insulating material and extending substantially arallel to the conductors of the cord, where y substantially all strain is removed from the conductors and the waterproof sheathing at the point where the conductors enter the terminal block.

A further feature of the invention is thel provision in a device of this character of a terminal contact block in which the conductors are permanently attached to the contacts and the block is molded or cast about the ends of the conductors and contacts.

A still further feature of the invention is the provision of resilient ridges surrounding the contact blocks which tend to absorb jars which would otherwise be transmitted to the contact member.

Other features and advantages will appear from time to time as the description of the invention progresses.

substantially on the line 3--3 of Figure 2;

Figure 4 illustrates a section substantially like that of Figure 3, but showing a modified arrangement b-y means of which the an-. chor strlps are yattached to the-terminal contact block;

Figure 5 is a section on the line 5-5 of Figure 2;

Figure 6 is a section on the line 6-6 of Figure 2;

Figure 7 is a section on the line 7-7 of Figure 2; and

Figure 8 is a section on the line 8-8 of Fi re 2.

ferring now to the drawings, 10 and 11 represent the conductors of the cord. Each of the conductors 10 and 11 is surrounded by insulating material 12 of any desired kind, but preferably of the typel in which the wire is immediately surrounded by insulating material as of rubber, or rubber composition, over which is laid a coverin of braided cotton or silk. The two insu ated conductors 13 and 14 thus formed are then twisted together to form a twisted pair, as

indicated in Figure 2.

To the ends of the conductors 10 and 11 are rigid'y secured the plug contacts 15 and 16. he condu-ctors are preferably rigidly secured to the plug contacts as by a soldered or similar connection. rIhe plug contacts 15 and 16 are provided intermediate their ends with enlarged portions 17 and 18 respectively. The terminal contact block 19 may be of any suitable insulating material, and is formed by being cast about the ends of the insulated conductors 13, and 14, and the plug contacts 15 and 16.

At their opposite ends, the conductorsl are joined to the socket contacts 20 and 21'respectively. The contact 20 is vformed as a screw threaded ring, and contact 21 as a rebent or V-shaped strip of conducting material mounted in the block 22 of insulating material in any desired manner. Block 22 Gli lill@ as shown in Figure 2 rests against the inturned edges of the ring forming contact 20. As in the case of the plug contacts shown at the left in Figure 2, the wires 10 and 11 are rigidly secured to the contacts 20 and 21, as by soldering or some similar manner. The contact block 23 is formed of suitable insulating material, and as in the case of the plug contact block 19, it is referably formed by being cast about the en s of the insulated conductors 13-14, the contact ring 20, and the insulating block 22.

Formed about the circumference of the plug block 19 is a plurality of projections 24. About the block 19 immediately in front of the lugs 2-'1 is a band 25 of wire, strong cord, or other suitable material. To the band 25 is secured one end of each of a plurality of anchor members 26. These anchor members, which may be formed of cord, wire or other suitable material, extend from the band 25 through the spaces between the lugs 24 and then substantially parallel to the twisted pair 13-14.

In the socket block 23, a circumferential groove 27 is formed, in which is a ring 28 of wire, cord, or other suitable material. A plurality of anchor members 29 is provided. Each of the members 29 has one end secured to the ring 28, the other end being arranged substantially parallel to the twisted pair 13-14, as shown in Figure 2.

Instead of the grooved arrangement 28 shown in Figure 2, the block 23 may be provided with a plurality of lugs 30, back of which the ring 28 may be placed in a manner similar to that employed in connection with the plug block 19. The terminal contact blocks 19 and 23 being attached to the' opposite ends of the twisted pair 13, and 14, and the anchor strips 26 and 29 being in place, there is molded about the entire structure a continuous waterproof covering 32 of rubber or other similar material. The anchor strips 26 and 29 will thus be imbedded in the waterproof covering, and will reduce to the minimum any strain which might otherwise be brought on the twisted pair at the point where they enter the terminal block. These anchor strips will also tend to reduce the strain which might otherwise be brought on the' waterproof covering where it joins the terminal blocks..

In the process of moldin the cover 32 about the twisted pair an the terminal blocks, the rubber or other material used will form closelyabout the lu s 24, and the circumferential ridges 31 a ut block 23. Thus, the insulating coverin will be caused to closely adhere to the b ocks and prevent ingress of water or moisture between the covering and the blocks.

It will thus be seen that in the structure provided, it is practically impossible for water to get to the conductors of the twisty shock in case the block is accidentally dropped. If desired, the ridges such as 33 and 34 may be formed to extend outfarther than shown in Figure 2.

In Figure 1, a modification of this arrangement is shown in which ridge 35 is shown extending outwardly a considerable distance from the block 23. The space between the ridge 35 and the smaller ridge 36 forms a groove in which may be secured the clamping member37 of a guard 38. In Figure 1, 39 indicates the usual incandescent light bulb representin merely one of' the devices which may e emplo ed with the socket member of the invention.

If desired, the protective covering 32 may be extended beyond the end of the block 23 to form a ring 40 so that when an electric light bulb or other device is inserted in the socket member, a water tight joint will be provided between the socket andthe device. The ring 40 may also be arranged to engage the covering of a plug block 19 so as to form a water tight connection in case it was desired to use two or more oi the extension cords in series by means of the usual screw-in plug sockets. With the enlarged .flange as 35, shown in Figure 1, the danger of the bulb 39 or its ilament being broken in case the device is dropped will be greatly reduced.

Although in the accompanying disclosure the cord is shown as provided at eachend with a contact device, its application obviously is not limited to 'a cord provided with a plurality of contact devices, but either one of those shown may be advantageously employed under certain circumstances.

I prefer to form the continuous waterproof insulating covering 32 of a good grade of rubber, such as is used in the treads of high class automobile tires, the covering beiljguvulcanized after. application.

' 'le in the drawings and above description certain specific details are disclosed, it is to be understood that modifications of these details are contemplated, and the invone end secured to said terminal block an extending parallel with said conductors, and a covering of flexible, waterproof material molded about and closel adhering to said conductors, terminal blocli and anchor members to form an integral whole.

2. An extension cord comprising conductors insulated from each other and formed into a twisted pair, a contact block, socket contacts in said block, means joining the adjacent ends of said conductors to said contacts respectively, another contact block, plug contacts in said block, means joining the opposite ends of said conductors to said plug contacts respectively, and a covering of flexible water roof material integrally molded about and) closely adhering to said twisted pair of conductors and the adjacent end and outer surface of each of said blocks.

3. An extension cord comprising conductors insulated from each other and formed into a twisted pair, a contact block, socket contacts in said block, means joining the adjacent ends of said conductors to said contacts respectively, another Contact block, plug contacts in said block, means joining the opposite ends of said conductors to said plug contacts respectively, flexible anchor members extending from each oi" said blocks parallel With the said conductors, and a covering of flexible waterproof material molded about and closely adhering to said com ductors, blocks and anchor members lo form an integral Whole.

In Witness whereof, I hereunto subscribe my name this 7th day of December. 1921.

LORNE A.. GRIFFIN.

Witnesses:

EDNA V. GUsTAFsoN, EMILE J. BoURGoIs. 

